Understanding the importance of selecting the correct spring rate for you.

No matter what you ride, spring rate is one of the most important aspects to setting up your machine so it works best for you and your application.

To many times do we hear how a rider got the sag to the desired level by cranking in or out on the spring collars; This is never the answer to setting your ride height no matter if you ride in the dirt or on asphalt. Can you get the rider sag with the incorrect spring or even a spring that is way to stiff or to soft? Sure you can but the bike will never ride correctly.

Example one: You buy a bike for your child and the previous owner was much lighter than him /her, you think the rear end bottoms over even small bumps so we will just crank down on the spring collars till it stops bottoming and turn the compression way in and wallah the issue is fixed.

This is wrong because the spring has no free travel when the shock is fully extended and every time the rear wheel leaves the ground and the spring is trying to rip the shock in two. Another possible problem may arise in the form of the spring coils binding depending on how much you tightened it and if this happens a few other things will most likely arise. Fatigue of the spring can cause the rate to weaken and over time become softer and eventually the spring will break, causing major damage to the shock and items around it as well as possible injury or death to the rider.

Example two: Same situation but this time the new owner is much lighter than the previous one so you think " we will just loosen the collars till the spring is no longer tight" and now the spring is floating around on the shock. You then crank the comp way out and think, ya this fixed it.

Sorry to say but; No it did not fix anything. What you did was remove all the preload in the spring so now the shock squats under a load and when ever the wheel leaves the ground the spring is rattling around on the shock causing damage the the shock body and bump stop. Eventually the most likely out come will be you will have destroyed the shock body and bump stop cup as well as the spring. All this time the bike will have bounced off the ground on landings and never turned well.

So how do keep this from happening? Understanding the difference from rider sag to static sag is a key tool to setting up your machine to handle best no matter what you ride.

One: Static sag and what it is for.

Static sag is the sag in which the bike or machine is under its own weight with out interference from the rider. This sag is measured by first placing the machine on a stand so the wheels do not touch the ground. You will then take a measurement from a point at the axle to a point that dose not move on the machine directly above the axle. Now remove the stand and set the machine on the ground. Once the machine is on the ground you will compress the front or rear depending on the axle you want to know the sag of and allow it to fully return to its natural height. Measure again at the same points as before and subtract the difference, this is your static sag.

Your sag can be altered and not be a reliable reading if the pivot points are not freely moving and a lack of service is present. So before any sag adjustment make sure the bearings are clean and well greased and if play is evident replace damaged components.

Two: Rider sag, often confused with determining race sag.

Rider sag is important but not for the reason you probably think it is. Rider sag is only for one purpose and that is to determine if the spring is the correct rate for you. Setting your "Rider sag" at the track before a race is complete bullsh*t, unless you plan to change to a different spring track side you are wasting your time.

Cranking up or down on the spring does "not" change the rate it changes the preload on the spring that then adjusts the pitch of the front or rear of the machine.

So how do I get rider sag? Simple, sit on the machine in race pose and measure the squat of the suspension just as you measured the static sag. Now subtract that number from the over-all measurement from when the machine was on a stand, that is your rider sag.

Is the measurement right for me? well this is where the static sag comes into place. Once you have compressed or released the spring enough to get the number you were after you now need to measure the static sag again, do you have any sag left or do you have way to much?

In most situations you will aim for 1/3rd of travel for rider sag and approximately 10mm of spring preload to achieve that, confused yet?

On a normal dirt bike say a 125cc up, with 10mm preload on the spring you will have about 38mm of static sag or 1.5 inches; That is your goal.

Now to get rider sag you will need to change springs up or down in rate until you have the rider sag number you want yet still have the 38mm of static sag. Once this is done you will never check rider sag at the track again, you will always check static sag and adjust the pitch of the bike based on that number. Your static sag will translate to the rider sag and the bike will handle as it should, at least spring wise.

There are exceptions to the rule but they are usually based on circumstances and should be determined by a professional suspension tech.